FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/rangecoder.h
Date: 2022-07-07 01:21:54
Exec Total Coverage
Lines: 54 54 100.0%
Branches: 22 22 100.0%
Line Branch Exec Source
1 /*
2 * Range coder
3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Range coder.
25 */
26
27 #ifndef AVCODEC_RANGECODER_H
28 #define AVCODEC_RANGECODER_H
29
30 #include <stdint.h>
31
32 #include "libavutil/avassert.h"
33 #include "libavutil/intmath.h"
34
35 typedef struct RangeCoder {
36 int low;
37 int range;
38 int outstanding_count;
39 int outstanding_byte;
40 uint8_t zero_state[256];
41 uint8_t one_state[256];
42 uint8_t *bytestream_start;
43 uint8_t *bytestream;
44 uint8_t *bytestream_end;
45 int overread;
46 #define MAX_OVERREAD 2
47 } RangeCoder;
48
49 void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size);
50 void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size);
51
52 /**
53 * Terminates the range coder
54 * @param version version 0 requires the decoder to know the data size in bytes
55 * version 1 needs about 1 bit more space but does not need to
56 * carry the size from encoder to decoder
57 */
58 int ff_rac_terminate(RangeCoder *c, int version);
59
60 void ff_build_rac_states(RangeCoder *c, int factor, int max_p);
61
62 1625049798 static inline void renorm_encoder(RangeCoder *c)
63 {
64 // FIXME: optimize
65
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 1728938857 while (c->range < 0x100) {
66
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 103889059 if (c->outstanding_byte < 0) {
67 9857 c->outstanding_byte = c->low >> 8;
68
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 103879202 } else if (c->low <= 0xFF00) {
69 68318150 *c->bytestream++ = c->outstanding_byte;
70
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 68937273 for (; c->outstanding_count; c->outstanding_count--)
71 619123 *c->bytestream++ = 0xFF;
72 68318150 c->outstanding_byte = c->low >> 8;
73
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 35561052 } else if (c->low >= 0x10000) {
74 34806731 *c->bytestream++ = c->outstanding_byte + 1;
75
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 34941926 for (; c->outstanding_count; c->outstanding_count--)
76 135195 *c->bytestream++ = 0x00;
77 34806731 c->outstanding_byte = (c->low >> 8) & 0xFF;
78 } else {
79 754321 c->outstanding_count++;
80 }
81
82 103889059 c->low = (c->low & 0xFF) << 8;
83 103889059 c->range <<= 8;
84 }
85 1625049798 }
86
87 827820 static inline int get_rac_count(RangeCoder *c)
88 {
89 827820 int x = c->bytestream - c->bytestream_start + c->outstanding_count;
90
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 827820 if (c->outstanding_byte >= 0)
91 827438 x++;
92 827820 return 8 * x - av_log2(c->range);
93 }
94
95 1625031496 static inline void put_rac(RangeCoder *c, uint8_t *const state, int bit)
96 {
97 1625031496 int range1 = (c->range * (*state)) >> 8;
98
99 av_assert2(*state);
100 av_assert2(range1 < c->range);
101 av_assert2(range1 > 0);
102
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 1625031496 if (!bit) {
103 711340249 c->range -= range1;
104 711340249 *state = c->zero_state[*state];
105 } else {
106 913691247 c->low += c->range - range1;
107 913691247 c->range = range1;
108 913691247 *state = c->one_state[*state];
109 }
110
111 1625031496 renorm_encoder(c);
112 1625031496 }
113
114 1510847429 static inline void refill(RangeCoder *c)
115 {
116
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 1510847429 if (c->range < 0x100) {
117 94018588 c->range <<= 8;
118 94018588 c->low <<= 8;
119
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 94018588 if (c->bytestream < c->bytestream_end) {
120 94016915 c->low += c->bytestream[0];
121 94016915 c->bytestream++;
122 } else
123 1673 c->overread ++;
124 }
125 1510847429 }
126
127 1510847429 static inline int get_rac(RangeCoder *c, uint8_t *const state)
128 {
129 1510847429 int range1 = (c->range * (*state)) >> 8;
130
131 1510847429 c->range -= range1;
132
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 1510847429 if (c->low < c->range) {
133 653417603 *state = c->zero_state[*state];
134 653417603 refill(c);
135 653417603 return 0;
136 } else {
137 857429826 c->low -= c->range;
138 857429826 *state = c->one_state[*state];
139 857429826 c->range = range1;
140 857429826 refill(c);
141 857429826 return 1;
142 }
143 }
144
145 #endif /* AVCODEC_RANGECODER_H */
146